The present invention relates to cooling structures of stators, which include a case that accommodates a rotating electrical machine, and cool a coil end portion protruding from a stator core included in the stator of the rotating electrical machine toward one side in a stator axial direction by supplying a cooling medium from the other side in the stator axial direction toward a cooling medium introducing gap that is formed between the inner surface of the case and the outer peripheral edge of one axial end face of the stator core.